@Override
            public String getIndexFieldId() {
                return "_id";
            }

            @Override
            public String getIndexFieldDocId() {
                return "doc_id";
            }

            @Override
            public String getIndexFieldBoost() {
                return "boost";
            }

            @Override

      },
      "expires": {
        "type": "date",
        "format": "date_optional_time"
      },
      "digest": {
        "type": "text",
        "index": false
      },
      "doc_id": {
        "type": "keyword"
      },
      "favorite_count": {
        "type": "long"
      },
      "filename": {
        "type": "keyword"
      },
      "filetype": {

            @Override
            public String getIndexFieldId() {
                return "_id";
            }

            @Override
            public String getIndexFieldDocId() {
                return "doc_id";
            }

            @Override
            public String getIndexFieldBoost() {
                return "boost";
            }

            @Override

        @Override
        public Integer getSuggestUpdateContentsLimitDocSizeAsInteger() {
            return 50000;
        }

        @Override
        public String getIndexFieldDocId() {
            return "doc_id";
        }

        @Override
        public String getIndexFieldClickCount() {
            return "click_count";
        }

        @Override
        public String getIndexDocumentSearchIndex() {

            @Override
            public String getIndexFieldId() {
                return "_id";
            }

            @Override
            public String getIndexFieldDocId() {
                return "doc_id";
            }

            @Override
            public String getIndexFieldBoost() {
                return "boost";
            }

            @Override

        @Override
        public String getIndexDocumentUpdateIndex() {
            return "fess.update";
        }

        @Override
        public String getIndexFieldDocId() {
            return "doc_id";
        }

        @Override
        public String getIndexFieldId() {
            return "_id";
        }

        @Override
        public String getIndexFieldVersion() {

            @Override
            public String getIndexFieldId() {
                return "id";
            }

            @Override
            public String getIndexFieldDocId() {
                return "doc_id";
            }

            @Override
            public String getIndexFieldBoost() {
                return "boost";
            }

            @Override

index.field.config_id=config_id
# Field name for expiration date in the index.
index.field.expires=expires
# Field name for URL in the index.
index.field.url=url
# Field name for document ID in the index.
index.field.doc_id=doc_id
# Field name for internal ID in the index.
index.field.id=_id
# Field name for version in the index.
index.field.version=_version
# Field name for sequence number in the index.
index.field.seq_no=_seq_no

    /** The key of the configuration. e.g. url */
    String INDEX_FIELD_URL = "index.field.url";

    /** The key of the configuration. e.g. doc_id */
    String INDEX_FIELD_doc_id = "index.field.doc_id";

    /** The key of the configuration. e.g. _id */
    String INDEX_FIELD_ID = "index.field.id";

    /** The key of the configuration. e.g. _version */